Decade Volcano: Merapi

Two factors that attract visitors from around the world to this very active Indonesian volcano are its natural beauty and the chance to see an eruption.

Quite a few geoscientists come here, too. Merapi’s frequent eruptions offer some rare research opportunities in a variety of fields.

Mount Merapi also produces more pyroclastic flows than any other active volcano in the world. (Oregon State University)

On a good day, these are fun to watch (though you must never let down your guard):

We will cover some of Mount Merapi’s bad, downright grim days farther down in the post.

This almost constant activity keeps Merapi’s summit free of vegetation. Nevertheless, crops and livestock thrive around the volcano and millions of people earn a living here.

A 2013 view of Merapi (right) from Yogyakarta. (Image: William Christiansen, CC BY 2.0)

A bird could fly 17 miles in a straight line from Merapi’s summit to downtown Yogyakarta.

The city is so big, though, that part of its metropolitan area extends onto Merapi’s southern flank.

Yogyakarta is the capital of Indonesia’s only officially recognized monarchy, ruled by a sultan. As well, it’s a major Javanese cultural center and a nationally renowned seat of higher learning.

In this picture from Klaten Regency, Merapi is on the left. Mount Merbabu, which hasn’t erupted since the late 18th century, is on the right. (Image: Abdillah Wicaksono)

Mount Merapi is also part of three Central Javan regencies — Magelang, Boyolali, and Klaten — and it forms a dramatic backdrop to the famous UNESCO World Heritage site, Borobudur Temple.

It became a Decade Volcano because of this combination of frequent volcanic violence and a large human population at risk.

Here is Merapi during a rare quiet spell.

There is a nature reserve up there, as well as villages almost all the way to the summit.

In one of those villages lived the most famous of Merapi’s “gatekeepers,” or spiritual guardians.

His story, as Wikipedia tells it, has an interesting modern twist.

As you might expect, the volcano looms large in local Javanese traditional beliefs.

This “gatekeeper,” Mbah Maridjan, was one of a long line of individuals appointed by sultans in Yogyakarta to soothe Merapi (see the link above for more details about the traditional beliefs behind this).

Mbah Maridjan became deputy gatekeeper in 1970 and replaced his father as Merapi’s spiritual guardian in 1983.

He became a national celebrity in 2006 after refusing to leave his station during an eruption. He was badly burned but survived and resumed work after five months in the hospital.

The interesting twist is that through this new-found fame he got work in advertising, promoting sports drinks!

Then Merapi erupted in 2010. Once again, Mbah Maridjan stayed. This time he died, along with more than ten other people who remained at his side.

Towards the end of the following video from October 26, 2010, you’ll see them refusing a ride as they sit along the side of a hut in the little village where Mbah Maridjan was born, just two miles from Merapi’s crater.

It’s a little like seeing Harry R. Truman alive less than an hour before Mount St. Helens blew, if Harry had been a religious leader and had already survived one pyroclastic flow.

No wonder this Yogyakarta media video has almost three million views!

But there are lessons for us laypeople here: the video very clearly shows how difficult it is to get away from an erupting volcano.

And if you linger, you endanger the lives of those who Mr. Rogers called “the helpers,” in this case, the people doing the filming and the driving.

The text and speech in this video are in Indonesian, but the visual experience tells the story clearly (with plenty of darkness and terror but no graphical images):

The eruptions this day began around 17:02 local time; pyroclastic flows (six, according to Wikipedia) began to diminish at around 18:54.

This was filmed about two miles from the summit during that time, so these people had good reason to be afraid.

It’s something you might want to remember if you are ever tempted to venture onto a volcano that has an elevated alert level (Merapi this day was on level 4, the highest, which is why the sirens were blowing).

The Decade Volcano Program and Merapi

There was reportedly more international collaboration at Merapi than at any other Decade Volcano. (European Volcanological Society)

Monitoring improved dramatically. As a result of the program, volcanologists at a central observatory in Yogyakarta could now follow Merapi’s seismic and other geological data signals almost in real time. (Newhall)

Newhall also wrote around the turn of the 21st century that, while scientists were now better prepared to handle Merapi’s common small eruptions, there was “inadequate preparation and monitoring” for big ones.

Nevertheless, ten years later, although almost 400 people (including Mbah Maridjan and his associates) died in Merapi’s first VEI 4 eruption since the 19th century, monitoring and emergency measures saved an estimated 10,000 to 20,000 lives.

Keep that in mind when you watch this next video, the really grim (but not graphic) one.

Earth processes like volcanism are so big that even our successes sometimes appear very, very small.

But we do succeed.

The following 12-minute video dates from November 4th, during the height of the 2010 eruption.

This is what happens when there is a major volcanic eruption in the midst of more than 20 million people.

Look for the helpers (of which there are many) and try to keep the bigger picture in mind — while these people’s lives were changed forever and they suffered great hardship, no one had to go up on the mountain after Merapi settled down and recover their bodies.


7.54°S, 110.446° E, on Java in Indonesia. The GVP Volcano Number is 263250.

Nearby Population:

Per the Global Volcanism Program website:

  • Within 5 km (3 miles): 49,205
  • Within 10 km (6 miles): 185,849
  • Within 30 km (19 miles): 4,348,473
  • Within 100 km (62 miles): 24,728,414

Current Status:

Per the latest report at the time of writing, Aviation Code Orange, status 2 on a four-point alert system.


  • Eruption styles: When it first appeared, at least 400,000 years ago, Merapi used to have runny red lava, sort of like a Hawaiian volcano. It was probably not as smooth-flowing as what we saw at Kilauea in 2018, though, and the lava only got stickier over time as its chemistry gradually changed. About 2,000 years ago, the edifice that had been built up over many millennia collapsed and the Merapi we see today began to take shape as the result of a combination of runny (effusive) and explosive eruptions. For the last 600 years, Merapi has had very sticky lava that either laps over the crater wall a little ways or else piles up into an unstable dome that is prone to collapses/explosions that trigger pyroclastic flows. (Global Volcanism Program; MVO archive)

    Another lethal problem at Merapi are lahars — the Indonesian word for mudflows. Sometimes it’s called “cold lava,” but this is really a mixture of water and ash that has the consistency of wet concrete and can knock down and carry away almost anything in its path.

    While melted snow and ice can cause lahars at some other volcanoes, those at Merapi usually form when heavy rain washes over freshly deposited hot ash from a pyroclastic flow (rain can also remobilize old ash flows).

    Here’s video of an especially large lahar, carrying along what appears to be an entire rock quarry!

  • Biggest recorded event: In addition to the 2010 eruption, Merapi had a VEI 4 eruption in 1872. (Global Volcanism Program) Per Brown et al., 230 people died in it.
  • Most recent eruption: At the time of writing, April 10, 2020. This is part of ongoing activity that began, after almost four years of quiet, on May 11, 2018 — much to the surprise of some nearby picnickers:

    Per Reuters, everyone who was on the volcano when it went off escaped harm.

  • Past history: See the GVP for details.


There is recent official mention of the Merapi Volcano Observatory, but all I could find is this archived site, which still has much good information but hasn’t been updated in almost two decades.

The MAGMA Indonesia page is a great way to quickly check on Merapi or any other Indonesian volcano.

Just use a browser translator on the menu (the graphic is only helpful if you already know which volcano you want and can read the Indonesian popup).

Featured image: Merapi erupting on March 3, 2020, by BPPTKG via Wikimedia, public domain.


Brown, S.K.; Jenkins, S.F.; Sparks, R.S.J.; Odbert, H.; and Auker, M. R. 2017. Volcanic fatalities database: analysis of volcanic threat with distance and victim classification. Journal of Applied Volcanology, 6: 15.

European Volcanological Society (SVE). n. d. Decade volcano program 1990/2000.

Global Volcanism Program: Mount Merapi. Last accessed May 28, 2018.

Merapi Volcano Observatory (MVO) archived pages. July 4, 1997.

Newhall, C. 1996. IAVCEI/International Council of Scientific Union’s Decade Volcano projects: Reducing volcanic disaster. status report. US Geological Survey, Washington, DC. Retrieved from

Oregon State University: Volcano World. n.d. Merapi. Last accessed April 12, 2020.

Surono, M.; Jousset, P.; Pallister, J.; Boichu, M.; and others. 2012. The 2010 explosive eruption of Java’s Merapi volcano—a ‘100-year’event. Journal of Volcanology and Geothermal Research, 241: 121-135.

Wikipedia. 2020. Mount Merapi. Last accessed April 12, 2020.

___. 2020. The 2010 eruptions of Mount Merapi. Last accessed April 20, 2020.

___. 2020. Mbah Maridjan. Last accessed April 12, 2020.

___. 2020. Special Region of Yogyakarta. Last accessed April 12, 2020.

___. 2020. Yogyakarta. Last accessed April 12, 2020.

Wikipedia (Indonesian). 2020. Gunung Merapi. Last accessed April 20, 2020, via Google Translate.

___. 2020. Mbah Maridjan. Last accessed April 20, 2020, via Google Translate.

___. 2018. Taman Nasional Gunung Merapi (Mount Merapi National Park). Last accessed May 28, 2018, via Google Translate.

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